By Rob Richie, Terry Bouricius, and Philip MacklinPublished October 12th 2001 in Science

Steven Brams and Dudley Herschbach are right about the defects in the
plurality voting system used in most U.S. elections (Editorial, "The
science of elections," 25 May, p. 1449). But, on both theoretical and
practical grounds, they are wrong to tout approval voting (AV) over
instant runoff voting (IRV).

Used for decades in Australia and Ireland and considered in 13 U.S.
state legislatures this year, IRV allows voters to rank candidates in
order of preference. A voter's best strategy is to sincerely rank the
candidates. If no candidate gets a majority of first preferences,
candidates at the bottom are sequentially dropped. Each ballot cast for
those eliminated candidates is added to the totals of the next choice
indicated on that ballot until a candidate achieves a majority. IRV
duplicates a series of traditional runoffs, but without the need for
additional elections that cost taxpayers and candidates more money and
often lead to falloffs in voter participation (1).

In contrast, AV is a binary system, where the voter can only indicate
"yes" or "no" for each candidate. The problem is that voters rarely
have binary views about a range of candidates. Assume a voter sees Z as
most favored, Y as less favored, and X as unacceptable. By voting for
"acceptable" candidates Y and Z, the voter could cause Z to lose. But
by voting only for Z, the voter makes it easier for X (the unacceptable
candidate) to win (2). The voter will be torn between voting
defensively against X or strategically for Z because voting for a
second choice counts directly against your first choice.

Approval voting has another important real-world flaw. Political
behavior has much to do with what is rewarded by the election system,
and AV would exacerbate one of the worst aspects of U.S. campaigns:
avoidance of substantive policy debate. Because a candidate could lose
despite being the first choice of an absolute majority of the
electorate (3), smart candidates would avoid controversial issues that
alienate any significant number of voters. Smiling more and using
policy-empty themes like "I care" will not clarify the important
choices leaders must make. Those rewarded by AV could be characterized
as "inoffensive" more than "centrist."

IRV strikes a better balance. It rewards candidates who stand out on
policy enough to gain first-choice support, yet encourages
coalition-building and fewer personal attacks as candidates seek to be
the second choice of other candidates' supporters.

These arguments help explain why IRV is used and proposed far more
often than AV, and why next year Alaska and San Francisco will hold
ballot measures to implement IRV for their major elections (see for
details). IRV is the right system for the United States' high-stakes
elections with a single winner.

Rob RichieTerry BouriciousPhillip Macklin

References and Notes:

1. Ireland's 1990 presidential race provides an example of how IRV
works. In the first round, Brian Lenihan won 44% of first choices, Mary
Robinson won 38%, and Austin Currie won 17%. After Currie's
elimination, Robinson had clear majority support. She won 53% to 47% in
the second round of counting. Without IRV, Currie would have been a
"spoiler" and handed the presidency to Lenihan.

2. Imagine an AV election with 100 voters. After 98 ballots are
counted, the results give 55 approval votes to candidate Z, 60 votes to
candidate Y, and 61 votes to candidate X. The two remaining ballots
were cast by those voters who really liked Z and intensely dislike X.
If knowing these results in advance, they would want to block candidate
X by casting votes for both candidates Y and Z. Now suppose the results
instead gave 60 approval votes to candidate Z, 61 to Y, and 55 to X.
The final two voters in this case would want to elect candidate Z by
not voting for Y. But only in imaginary elections can we know the
results in advance. Without that advance information, supporters of
candidate Z are in a quandary-as, in fact, are supporters of other
candidates. IRV's alleged mathematical deficiencies, on the other hand,
have almost no strategic impact because they depend on voters making
complex calculations with advance knowledge of election results"

3. Here is how AV can allow a candidate with strong majority support to
lose in an election with 100 voters. Under plurality voting, Candidate
A is the favorite choice of 65 voters, candidate B is preferred by 25,
and candidate C is the top choice of only 10. Candidate A is the
unambiguous winner, and C is a distant third. Under AV, however, many
voters might pick C as a weak, but tolerable alternative. The final
count might give 70 approval votes to A, 35 votes to B, and 75 votes to
C. Candidate C would win.